1. Field of the Invention
This invention relates to the catalytic purification of tertiary butyl alcohol prepared by the reaction of propylene with tertiary butyl hydroperoxide. More particularly, this invention relates to a method for the removal of residual contaminating quantities of tertiary butyl hydroperoxide and ditertiary butyl peroxide from a tertiary butyl alcohol feedstock which is prepared by the reaction of propylene with tertiary butyl hydroperoxide and is useful as an octaneenhancing component for motor fuels. In accordance with the present invention the peroxide-contaminated feedstock is brought into contact with a catalyst which is composed of iron, copper, chromia and cobalt in order to substantially selectively decompose both the tertiary butyl hydroperoxide and the ditertiary butyl peroxide to tertiary butyl alcohol.
2. Prior Art
a. Process
A process for the manufacture of substituted epoxides from alpha olefins such as propylene is disclosed in Kollar U.S. Pat. No. 3,351,653 which teaches that an organic epoxide compound can be made by reacting an olefinically unsaturated compound with an organic hydroperoxide in the presence of a molybdenum, tungsten, titanium, columbium, tantalum, rhenium, selenium, chromium, zirconium, tellurium or uranium catalyst. When the olefin is propylene and the hydroperoxide is tertiary butyl hydroperoxide, propylene oxide and tertiary butyl alcohol are coproducts. U.S. Pat. No. 3,350,422 teaches a similar process using a soluble vanadium catalyst. Molybdenum is the preferred catalyst. A substantial excess of olefin relative to the hydroperoxide is taught as the normal procedure for the reaction. See also U.S. Pat. No. 3,526,645 which teaches the slow addition of organic hydroperoxide to an excess of olefin as preferred.
Stein, et al. in U.S. Pat. No. 3,849,451 have improved upon the Kollar process of U.S. Pat. Nos. 3,350,422 and 3,351,635 by requiring a close control of the reaction temperature, between 90.degree.-200.degree. C. and autogeneous pressures, among other parameters. Stein et al. also suggests the use of several reaction vessels with a somewhat higher temperature in the last vessel to ensure more complete reaction. The primary benefits are stated to be improved yields and reduced side reactions.
It is known that isobutane can be oxidized with molecular oxygen to form a corresponding tertiary butyl hydroperoxide and that the oxidation reaction can be promoted, for example with an oxidation catalyst (see Johnston U.S. Pat. No. 3,825,605 and Worrell U.S. Pat. No. 4,296,263.
Thus, tertiary butyl alcohol can be prepared either by the direct thermal or catalytic reduction of tertiary butyl hydroperoxide to tertiary butyl alcohol or by the catalytic reaction of propylene with tertiary butyl hydroperoxide to provide propylene oxide and tertiary butyl alcohol.
It is also known that tertiary butyl alcohol can be used as an octane-enhancing component when added to a motor fuel, such as gasoline. Thus, it has heretofore been proposed, as shown, for example, by Grane U.S. Pat. No. 3,474,151 to thermally decompose tertiary butyl hydroperoxide and ditertiary butyl peroxide to form tertiary butyl alcohol. The thermal decomposition must be conducted with care, as pointed out by Grane, in that tertiary butyl alcohol will start to dehydrate at a temperature of about 450.degree. F. and in that the dehydration becomes rapid at temperatures above about 475.degree. F. Moreover, the product from the thermal decomposition normally contains a minor amount of tertiary butyl hydroperoxide and ditertiary butyl peroxide which have an adverse effect upon the quality of motor fuels and must be substantially completely removed if the tertiary butyl alcohol is to be fully effective. Grane proposes to accomplish this thermally by heating tertiary butyl alcohol containing small quantities of such peroxides at a temperature of 375.degree.-475.degree. F. for a period of 1 to 10 minutes.
This concept was expanded upon by Grane et al. in U.S. Pat. Nos. 4,294,999 and 4,296,262 to provide integrated processes wherein, starting with isobutane, motor-fuel grade tertiary butyl alcohol was prepared by the oxidation of isobutane (e.g., in the presence of a solubilized molybdenum catalyst) to produce a mixture of tertiary butyl alcohol and tertiary butyl hydroperoxide from which a fraction rich in tertiary butyl hydroperoxide could be recovered by distillation. This stream, after being debutanized was subjected to thermal decomposition under pressure at a temperature of less than 300.degree. F. for several hours to significantly reduce the concentration of the tertiary butyl hydroperoxide. However, the product of this thermal decomposition step still contained residual tertiary butyl hydroperoxide, most of which was thereafter removed by a final thermal treatment of the contaminated tertiary butyl hydroperoxide in the manner taught by Grane U.S. Pat. No. 3,474,151.
Thus, the removal of trace quantities of tertiary butyl hydroperoxide from motor grade tertiary butyl alcohol has received appreciable attention. However, little appears to have been published concerning the removal of trace quantities of ditertiary butyl peroxide, the more refractory of the two peroxides. This may be explainable both because ditertiary butyl peroxide is not always present in trace quantities in motor grade tertiary butyl alcohol (its presence or absence being a function of the reaction conditions used in oxidizing the isobutane starting material) and because, when present, it is present in significantly lower amounts. For example, after decomposition of the major amount of tertiary butyl hydroperoxide formed by the oxidation of isobutane, the tertiary butyl hydroperoxide residual content will normally be about 0.1 to about 1 wt. %, based on the tertiary butyl alcohol, while the residual ditertiary butyl peroxide content, if any, will only be about 0.1 to 0.5 wt. %.
Sanderson et al. U.S. Pat. No. 4,547,598 discloses the use of unsupported cobalt borate and cobalt borate supported on titanium dioxide to decompose organic hydroperoxides to alcohols. It has also been proposed to remove the residual hydroperoxide contaminants from tertiary butyl alcohol through the use of a heterogeneous cobalt oxide catalyst containing a copper oxide promoter as shown, for example, by Coile U.S. Pat. No. 4,059,598. Allison et al. in U.S. Pat. No. 3,505,360 have more generically taught that alkenyl hydroperoxides can be decomposed catalytically through the use of a catalyst based on a metal or compound of a metal of group IV-A, V-A or VI-A.
Other prior art patents relating to the production of hydroperoxides, but not with the problem of residual tertiary hydroperoxide contamination and tertiary butyl alcohol include patents such as Rust U.S. Pat. No. 2,383,919; Harvey U.S. Pat. No. 3,449,217; Poenisch et al. U.S. Pat. No. 3,778,382 and Williams et al. U.S. Pat. No. 3,816,548.
In West German DE No. 3248465-A a two-step process is disclosed wherein isobutane is oxidized noncatalytically with air to a conversion of about 48-90% to form the corresponding hydroperoxide, which is then catalytically decomposed under hydrogenation conditions in the presence of a supported catalyst such as palladium, platinum, copper, rhenium, ruthenium or nickel to form tertiary butyl alcohol. The decomposition product obtained using 1.3% palladium on lithium spinel as a catalyst contained significant quantities of acetone, water and methanol.
Mabuchi et al. U.S. Pat. No. 4,112,004 discloses a process for preparing monohydric or polyhydric alcohols from organic peroxides in the presence of a nickel catalyst by continuously feeding a solution of the organic peroxide (e.g., butadiene peroxide) and a suspension of the nickel catalyst to a reactor in a controlled ratio and continuously withdrawing reaction mixture at a rate adequate to maintain a constant weight and composition of the reaction mixture in the reactor.
In U.S. Pat. No. 4,123,616 to Mabuchi et al. a process is disclosed for hydrogenating an organic peroxide to the corresponding mono- or polyhydric alcohol in a suspension or fluidized bed process under hydrogen pressure in the presence of a nickel catalyst. Examples are given showing the conversion of butadiene peroxide to 1,4-butane diol and 1,2-butane diol and the conversion of tertiary butyl hydroperoxide to tertiary butyl alcohol.
b. Catalysts
Godfrey U.S. Pat. No. 3,037,025 discloses the preparation of N-alkyl substituted piperazines using catalyst compositions consisting of the metals and oxides of copper, nickel and cobalt (including mixtures thereof) which may also be promoted by the inclusion of a normally non-reducible metal oxide such as chromium, aluminum, iron, calcium, magnesium, manganese and the rare earths. Preferred catalyst compositions are indicated as containing from about 44 to about 74 wt. % of nickel, about 5 to about 55 wt. % of copper and about 1 to about 5 wt. % of chromia.
Moss U.S. Pat. No. 3,151,112 discloses catalyst compositions useful for the preparation of morpholines including one or more metals from the group including copper, nickel, cobalt, chromium, molybdenum, manganese, platinum, palladium and rhodium, which may also be promoted with normally nonreducible oxides such as chromium oxide, molybdenum oxide and manganese oxide. Representative catalyst compositions include those containing from about 60 to about 85 wt. % of nickel, about 14 to about 37 wt. % of copper and about 1 to about 5 wt. % of chromia. Nickel, copper, chromia catalysts are also disclosed in Moss U.S. Pat. No. 3,151,115 and Moss U.S. Pat. No. 3,152,998.
Winderl et al. U.S. Pat. No. 3,270,059 teaches the use of catalysts containing a metal of groups I-B and VIII of the Periodic System. Examples of suitable catalysts are stated to be copper, silver, iron, nickel, and particularly, cobalt.
Boettger et al. U.S. Pat. No. 4,014,933 discloses catalysts containing cobalt and nickel promoted with copper such as those containing from about 70 to about 95 wt. % of a mixture of cobalt and nickel and from about 5 to about 30 wt. % of copper.
Habermann U.S. Pat. No. 4,152,353 discloses catalyst compositions comprising nickel, copper and a third component which may be iron, zinc, zirconium or a mixture thereof such as catalysts containing from about 20 to about 49 wt. % of nickel, about 36 to about 79 wt. % of copper and about 1 to about 15 wt. % of iron, zinc, zirconium or a mixture thereof. Similar catalyst compositions are mentioned in Habermann U.S. Pat. No. 4,153,581.
European patent application No. 0017651 filed Oct. 20, 1980, contains a disclosure of catalyst compositions related to those disclosed by Habermann, such catalyst compositions being composed of nickel or cobalt, copper and iron, and zinc or zirconium such as compositions containing 20 to 90% cobalt, 3 to 72% copper and 1 to 16% of iron, zinc or zirconium and catalyst compositions containing 20 to 49% nickel, 36 to 79% copper and 1 to 16% of iron, zinc or zirconium.
German Offen. No. 2,721,033 discloses a catalyst composition containing 35% nickel, about 87.5% iron and a minor amount of chromia.
Johansson et al. U.S. Pat. No. 3,766,184 discloses catalyst compositions composed of iron and nickel and/or cobalt.
Grane et al. in their U.S. Pat. Nos. 4,294,999 and 4,296,262 teach the removal of contaminating quantities of tertiary butyl hydroperoxide and ditertiary butyl peroxide by a short high temperature thermal treatment. However, thermal composition in this manner normally results in the formation of oxygenated products such as acetone and methanol, which are also deliterous to the quality of the final tertiary butyl alcohol motor fuel product.
Copending Sanderson et al. U.S. patent application Ser. No. 06/879,660 filed June 27, 1986, and entitled "Catalytic Purification of Tertiary Butyl Alcohol" discloses a process for purifying tertiary butyl alcohol wherein tertiary butyl hydroperoxide and ditertiary butyl peroxide impurities contained therein are selectively reduced in the presence of a specially proportioned nickel, copper, chromia, iron oxide catalyst.